Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
This paper presents the findings of an experimental research to investigate the\nperformance of axially restrained elliptical hollow (EHS) steel columns subjected\nto severe hydrocarbon fire. The test programme involved 12 steel columns\npresenting 2 oval sections 200 Ã?â?? 100 Ã?â?? 8 mm and 300 Ã?â?? 150 Ã?â?? 8 mm and\nyielding 2 slenderness Ã?» = 51 and 33. The 1800 mm columns were tested under\nloading ratios ranging between 0.2 and 0.6 of the ultimate strength determined\nusing EC3 and under axial restraint degree ranging from 0 to 0.16.\nThe obtained results of axial displacements, lateral displacements, measured\nrestraint forces, and high temperatures are presented in the paper. It was\nfound that introducing restraint to the columns with elliptical section produces\nhigh restraint forces which reduce the time to lose lateral stability. This\nis more evident in cases of lower load ratios than the higher load ratios. The\nnumerical study presented in this paper involved building a finite element\nmodel to simulate the columns behaviour in fire. The model was validated\nusing the test results obtained from unrestrained and restrained columns fire\ntests. The model demonstrated good agreement in the prediction of failure\ntimes and failure mechanisms of local and overall buckling. The FEM model\nwas then used to conduct a parametric analysis involving factors of slenderness,\nrestraint and loading. The conclusions drawn for this research are presented\nat the end of the paper....
The study on preparation technology of recycled concrete with economical and technical feasibility has gained more serious\nattention in each country due to its involvement and effect on the environment protection and the sustainable development of\nhuman society. In this study, we conducted a control variable test to investigate and assess the influence of the aggregate size on the\nstrength characteristics of concrete with different diameters of recycled aggregates. Concrete with recycled aggregates of 515mm\n(A), 1520mm (B), 2030mm (C), and their combinations were subjected to a series of unconfined pressure tests after curing for\n28 days. Based on the results obtained from the tests, an effort was made to study the relationship between the mechanical\ncharacteristics of recycled aggregate concrete and aggregate particle size. Also, a regression model of recycled concrete was\nproposed to predict the elasticity modulus and to adjust the design of mixture proportion. It is believed that these experiment\nresults would contribute to adjust the remediation mixture for recycling plants by considering the influence of recycled\naggregate size....
Seismic fragility of steel-sheathed cold-formed steel-framed (CFSF) structures is scarcely investigated; thus, the information for\nestimation of seismic losses of the steel-sheathed CFSF buildings is insufficient. This study aims to investigate the seismic fragility\nof steel-sheathed CFSF buildings with different wall configurations. Analytic models for four 2-story steel-sheathed CFSF\nbuildings are established based on shaking table tests on steel-sheathed CFS walls. Then, a group of fragility curves for these\nbuildings are generated. The results show that the thickness of steel sheathing and the fastener spacing of the wall have significant\nimpact on seismic fragility of steel-sheathed CFSF buildings. The seismic fragility of the CFSF building can be reduced by\nincreasing the thickness of steel sheathing or decreasing the fastener spacing. By increasing the thickness of steel sheathing, the\nreduction on probability is more obvious for the CP limit. It is also found that the exceeding probability is approximately linear\nwith fastener spacing, with a slope in the range from 0.25%/mm to 0.50%/mm....
Purpose. Physical expansion of urban areas and cities is of great importance nowadays. Irreparable damages will thus be caused by\nlack of proper planning against natural disasters. Crisis management will therefore guide through prevention, preparedness,\ndisaster relief, and recovery by planning an appropriate program. Methodology. Principal processes of crisis management against\nearthquake in Iran were evaluated and discussed. Multicriteria earthquake crisis management was then proposed by means of\nAnalytic Hierarchy Process (AHP). Vulnerability of 19 urban areas in Qazvin city was studied and analyzed as a case study. Three\nmain criteria were considered as ââ?¬Å?physical dimensions and physical vulnerability texture,ââ?¬Â ââ?¬Å?the amount of urban texture responsibility\nto aid after crisis,ââ?¬Â and ââ?¬Å?possibility of city reversibility after the crisis.ââ?¬Â These criteria were divided into 20 subcriteria\nwhich were prioritized by a questionnaire survey. Findings. ââ?¬Å?High population density,ââ?¬Â ââ?¬Å?urban texture of old and repairable\nbuildings,ââ?¬Â ââ?¬Å?lack of relief and medical services,ââ?¬Â ââ?¬Å?a few organic texture areas,ââ?¬Â ââ?¬Å?sidewalks with less than 6 meters width in the\nregion,ââ?¬Â and ââ?¬Å?lack of open spaces in the areaââ?¬Â were concluded to be the most important reasons causing high vulnerability of urban\ntexture in Qazvin city....
Nanomaterials have been widely used in the past few decades due to their\nproven capacity to enhance the mechanical properties of materials. While\nmany studies have sought to improve the understanding of how nanomaterials\naffect the behavior of concrete, additional research is needed in order to\nachieve the full potential of the material, especially in the presence of supplementary\ncementitious materials. This study aims to investigate the mechanical\nproperties of cement mortars incorporating both nano-silica (NS) and class F\nfly ash (FA). Furthermore, mercury intrusion porosimetry (MIP) was performed\nto study its effect on pore characteristics, and thermogravimetric\nanalysis (TGA) was performed to measure the calcium hydroxide Ca(OH)2\ncontent in the mixtures. It was found that using nano-silica enhances the\ncompressive strength, reduces the total porosity and accelerates the pozzolanic\nreaction....
Loading....